


and take your foot off the brake

by nilchance



Category: Undertale (Video Game)
Genre: Additional Warnings In Author's Note, Alternate Universe - Underfell, Dubious Consent, Ecto-Genitalia (Undertale), M/M, Past Prostitution, Past Sexual Assault, Sibling Incest, Soul Sex, Underfell Papyrus, Underfell Sans
Language: English
Status: Completed
Published: 2017-05-03
Updated: 2017-05-03
Packaged: 2018-10-27 10:52:59
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,421
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10807623
Author URL: https://archiveofourown.org/users/nilchance/pseuds/nilchance
Summary: It's possibly the nicest thing Papyrus has said to him in months. Years.Sans goes for his throat.





	and take your foot off the brake

**Author's Note:**

> detailed content warnings in the end notes

The mattress dips behind him. Sans comes up swinging, a bone shard in his fist, and someone catches his wrist. Leather gloves, the scent of smoke. Papyrus.

Rolling over to glare at Papyrus properly, Sans complains, "What the fuck, asshole, I could've stabbed you."

Papyrus glowers back. "I'm terrified. You were yelling."

Sans yanks his wrist out of Papyrus's grip. "And here I thought the great and terrible Papyrus doesn't need sleep."

Unceremoniously, Papyrus grabs Sans by the cervical spine (which: _ow_ ) and drags him out of bed. Sans stumbles the first couple steps, uncoordinated with sleep and adrenaline, and Papyrus just drags him. It's keep up or be choked. Sans keeps up.

The door to Papyrus's bedroom is flung open. Papyrus hauls Sans there by the scruff like a misbehaving guard dog, then shoves him onto the stupid racecar bed they brought from the dump. Sans bounces off the mattress and lays there, stunned.

"What the fuck," Sans repeats, because it definitely still applies.

Papyrus pushes at his shoulder. "I wasn't staying in your room. It's disgusting."

Grudgingly, Sans scoots over. Knowing that the door is at his back makes his spine prickle. "Nobody asked you to stay. What're you doing?"

Papyrus crawls into bed. There isn't room for both of them, not really. Papyrus is close enough to bite, a solid wall of bone and heat against the front of Sans's body.

"Trying to get a moment of fucking peace," Papyrus says impatiently. "Roll over."

There's an implicit 'or else' in that order. Sans rolls over. Papyrus drops a heavy arm over his stomach and drags him back against Papyrus's body.

When Papyrus speaks, Sans can feel the rumble of his voice. "Now go to sleep."

"Are we fucking spooning?" Sans asks no one in particular. Reality, maybe.

"Don’t ask stupid questions."

"I can't sleep like this."

"Why the hell not? You can sleep anywhere else." Papyrus spreads his hand on Sans's sternum. It's big enough to cover his whole ribcage. Sans shivers. It would be so easy for Papyrus to just slide his hand down the front of Sans's boxers. He doesn't. "Be lazy and useless. You're good at that."

Papyrus is as good as a wall at his back. Better, even, because Papyrus will murder anyone who tries to come through that door. He's dangerous, a blade with no hilt, but Sans would rather cut his hand to the marrow than have no blade at all.

Abruptly Papyrus asks, “You said you don’t dream.”

“I don’t. ‘S just another fucking night terror.” 

“You were screaming about Gaster again.”

As always, the name strums Sans’s raw nerves and he flinches.

Papyrus tightens his grip a little. “I killed him."

_There is dust inside of Sans. There is Gaster's dust inside of him. Papyrus killed him that fast, that Gaster didn't even get to pull out first and Sans will never never never get him out--_

"Are you listening?" Papyrus demands.

It yanks Sans back to the present like a leash. Distantly, Sans realizes he's gone rictus-stiff and he forces his body to relax. To yield. Papyrus likes it when he yields.

It hurts less when he yields.

"He's gone," Papyrus says. "Stop flinching at ghosts. You're pathetic enough as it is."

Sans laughs, a harsh bark of sound. "You shouldn't talk about somebody who's listening."

"Let him listen. He can't do anything else." Papyrus is growling, bristled up, but there's an edge of petulance in his voice. "I told you I'd kill anyone who puts a hand on you, and if I've got to kill some stupid fuck twice, I will."

It's possibly the nicest thing Papyrus has said to him in months. Years.

Sans goes for his throat.

He's got no chance, of course. Papyrus is stronger, bigger, faster, and he's been trained by Undyne. All the dirty fighting in the world (and Sans _is_ fighting dirty; Papyrus has long scratches where Sans raked his bad eye) won't balance the scales. Sans makes him work for it.

In less than a minute, Papyrus has Sans flat on his back on the floor. They rolled off the bed somewhere in there. Papyrus holds him by the wrists, nearly pulling Sans's shoulders out of socket. It hurts. Not even in a sexy way, it just fucking hurts.

Sans could dodge. Teleport. They both know he could evade most of the hits Papyrus throws his way and that he doesn't bother. Why not just stand there and take it? Why fucking not?

"You fucking bitch," Papyrus says.

Sans cackles and hears his sanity creak in it. He should stop, probably, but the surprised look on Papyrus's face, the blood dripping down onto Sans, is too goddamn funny. It's like a snow puff gnawed on Papyrus's ankle. Something tame and fluffy gone feral.

Yeah. Sans ought to do this more often. He'll lose, like he always does, but it's better than Papyrus thinking he's safe. Next thing they know, Papyrus might stop smacking him around. Like Sans deserves better.

Somebody needs to claw the sweetness out of Papyrus like a weed before it takes root. Kill or be killed, and Papyrus is never going to be the second. Not if Sans has anything to say about it.

Papyrus shakes him like a ragdoll even as he knifes healing magic into him. Sans's HP doesn't even drop. They're old pros at this. Papyrus could teach a master class on how to rough up somebody with one HP without ever letting him die.

Head still spinning, Sans grinds his hips into Papyrus's. He doesn't have much room to do it, and he's not even really into it, but that little bit of friction is sweet.

Papyrus looks down at him. To anybody else, his face would be blank as a stone, but Sans can see (beneath anger and stung pride) a flicker of interest.

Leaning his aching head back, Sans gives Papyrus his throat. The collar's still on it, a happy accident of Sans being too exhausted last night to take it off. Papyrus's gaze drops to the collar like it's a magnet, and Sans rocks his hips again.

"You could get off me," Sans says, the last of his manic laughter still in his voice. "Or you could just, uh, get off. 'S no skin off my nose. Seeing as I don't have skin or a--"

Papyrus bites his collarbone. Just sets his teeth in and gnaws like he's planning to leave behind a neat circle of marks. The dull ache of it spikes straight to Sans's head.

Well. Sans can work with this. His fight-or-flight reflexes are all replaced with one that says fucking is an A+ solution to most threats, and it's not like he's never conjured a cunt or dick when he's not turned on. His body is a distant machine but he can still flip the right switches.

Pressed up close as they are, Papyrus must feel the shift in Sans's magic. Papyrus tenses, his grip on Sans's wrists tightening just a little.

Sans flexes his fingers. "I attacked you. I oughta pay for it."

Papyrus stops biting down, leaving a hot wet brand on Sans's clavicle that could be spit or marrow. He lets go of Sans's wrists and props himself up on his elbows. The scratches on his face have almost stopped bleeding already. He's squinting a little as he studies Sans.

Since Sans's hands are loose and all, he puts them on Papyrus's narrow ass and pulls their hips together. "C'mon. It's not that goddamn complicated. Hurt me."

"Give me your soul."

Sans locks up. His brain is a busy signal and a screen flashing _nope nope nope_. Voice all tight and wrong, he says, "Why?"

Bad question. That'd usually be good for getting Papyrus angry, but he only says, steady as a metronome, "If you want me to fuck you, you'll do it."

And Sans isn't 100% sure he wants Papyrus to fuck him at all, but he wants this to be over. He wants to shake off this weak, jittery mood. Fucking is familiar territory, something Sans can do without even getting out of bed.

"Fuck, fine!" Sans plants a hand on Papyrus's chest and shoves, which gets him exactly nowhere. Another thing that ought to put Papyrus into one of his towering rages. "You gotta move."

Papyrus shifts his weight just as far as he has to, still pressing Sans heavily into the floor. Sans hates that he's grateful for it.

Yanking up his shirt, Sans exposes his ribs and the soul pulsing underneath. "Knock yourself out."

Arching an eyebrow, Papyrus says, "I told you to take it out and give it to me."

If it wouldn't hurt like fuck, Sans would _throw_ the damn thing at him. Instead he jerkily pulls it free and holds it out, hoping all his surliness and irritation smacks Papyrus as soon as he touches it. "There. You happy?"

"Rarely." Papyrus pulls off his gloves with his teeth and takes Sans's soul in his bare hands.

Sans hisses between his teeth. As weird as soul touching already is, it's weirder with no barriers, bone to bone. More intimate, which means more chances to get fucked up.

"Stop squirming," Papyrus says without raising his eyes from the soul. He isn't even stroking it with his thumbs or trying to lick it, just _looking_ , like all Sans's mistakes are written there and he's taking notes for later.

It's an ominous thought, one that ought to cause a spike of nervousness, but it just doesn't come. Like there's something in the way.

"What are you doing?" Sans says. He feels warmer, the hectic rattle of his brain slowing down. There's a faint glow around Papyrus's fingers, feeding magic into Sans's soul.

"Holding the leash. Stop fighting me." Smirking, pleased with himself, Papyrus mimics, "It's not that goddamn complicated."

If Sans had his legs free, he would kick him. That'd be easier that dealing with the sudden spike of shame that he's so weak that Papyrus has to do this. That he can't control his own fucking thoughts.  

"Of course you can't," Papyrus says, dismissive. "What else is new. It's not your job to think about it."

It's as good as a hard tug on the collar, reminding Sans of his place. The twin flares of resentment and relief blind him, and he goes limp. Maybe if his body doesn't resist, then his head will fall in line.

"Good." Papyrus says it in the same tone he'd use for an insult. His body frames Sans's, surrounds him in the scent of leather, dust and bone. He isn't letting up one bit of pressure. "Stay."

If Sans was in his right head, he'd bite Papyrus like the dog he's supposed to be. Or maybe that's his wrong mind and this quiet is the right one.

From here he can see the surface of Papyrus's thoughts, that cold calm hiding swift darkness somebody could drown in. Sans doesn't they to reach deeper. Papyrus already hates how well Sans can read his expression, and if Sans pisses him off this could go real bad.

Like Gaster--

Papyrus hisses irritation and shoves that thought away before Sans can even try. In its place, like a flashbulb bright, Papyrus shows him

_the vulnerable arch of Gaster's back and the satisfying thunk of a sharpened bone into his soul, the cry of pain as Gaster died much too fast, the burst of his dust and through its haze there's Sans, empty-eyed and broken and alive, thank fuck, Papyrus had given him up for dead but he's still alive, and Papyrus is going to keep him that way if he has to empty this entire pointless world._

Papyrus doesn't yank the memory away. It's more contempt than tenderness. They both know that he can give Sans a knife because Sans is too weak to ever try to kill Papyrus with it. Sans might bite and scratch and struggle, but it doesn't change a thing. Sans loves him. The end.

"I hate you the least," Papyrus says. Deliberately, he runs his thumb across the surface of Sans's soul, pleasure as a reward for good behavior. "Sometimes you're even tolerable."

"Careful, boss. All this sweet talk and you'll turn a boy's head."

"More tolerable when your mouth is shut." Papyrus shifts the soul to one hand and reaches the other between their bodies. With no particular preamble, he slides his hand into Sans's boxers. "Or when I'm fucking you. Should I?"

It takes Sans a long few seconds to realize that Papyrus is genuinely asking. Now that he's not jittering out of his bones, he's aware of the steady pulse of his neglected magic between his legs. He can't spread his legs, but he pushes up into Papyrus's hand. "Yeah, you really should."

One long finger slips between the lips of Sans's cunt. Even though he's expecting it, he jolts.

"At least you're wet," Papyrus says evenly, like he's not breathing a little faster now. With his slick finger, he rubs a slow circle around Sans's clit. When Sans convulsively grabs at his shirt, Papyrus grunts. "I'm not one of your tricks. You won't fake it with me. Do you understand?"

There isn't a threat of _or I'll kick your ass_ in Papyrus's question. It’s that he’ll stop fucking Sans entirely. There are ways Papyrus will hurt him and ways Papyrus won't. Lines even Papyrus won't cross because

_those first few weeks in Snowdin, Sans too placid and too quiet, Sans who doesn't react when Papyrus hits him and who doesn't tell stupid jokes, who lets Papyrus fasten the collar around his throat, who is dry-eyed during the day but weeps in his sleep and scours the bones of his pelvis raw trying to get out the dust, Sans falling--_

That time Papyrus tears the memory away. Sans lets him, because there are things he'd rather forget. Denial is working great for him, thanks.

"Yeah." Sans tries to radiate that yes, he understands, he won't get his trauma cooties all over Papyrus, he is the sincerest. Out loud, he says, "For starters, you don't gotta pay me."

Whatever Papyrus hears through the connection seems to settle his ass down. Brusque, he removes his hand from Sans's boxers and ignores Sans's complaining whine. He continues to ignore it when he gets off Sans entirely. "I know I don't. Get on the bed."

"Pap," Sans groans. Papyrus narrows his eyes like they both didn't just feel how much he likes being called that. "The floor's fine."

"No," Papyrus says bluntly. He's up the bed already, a pretty picture with his legs open and a telltale glow of red magic between his thighs.  He prods Sans with the tip of his boot. "I'm not listening to you bitch about your back tomorrow. Come here."

Grudging, Sans goes. It feels like he's righteously fucked up on weed or one of Alphys's pills, loose-limbed and warm. He doesn't bother to get up, just crawls to Papyrus and leans between his legs; Papyrus goes all tense, his eye-lights shrinking to almost nothing.

"Hey," Sans begins smugly, and doesn't get any further before Papyrus is hauling Sans up onto his lap.

Since Papyrus seems busy with trying to manhandle Sans's boxers off without putting down his soul, Sans gets Papyrus's dick out. When the zipper rips right off its track, Papyrus stops and _looks_ at him.

"Oops," Sans drawls. Curling his fingers around Papyrus's cock, he skims his thumb across the head. "Heh. Looks like you need a hand, boss."

Papyrus's fingers tighten fractionally around Sans's soul until Sans chokes a little and has to drop his forehead onto Papyrus's chest. Mutually assured destruction.

Panting, Sans shifts so that he can guide Papyrus's dick to his cunt with a brief stop to slick it all up with his dripping wetness. "Lemme help you out."

He takes Papyrus's cock in one go, empty to full in less than one breath. It burns some, makes him hiss "aw shit, fuck you, you big-dicked motherfucker!"

Papyrus laughs at him, mean, even though Sans can feel the fine tremor of his thighs and the arm he's got locked around Sans's hips. Even better is the backwash of Papyrus's pleasure getting Sans hotter, a feedback loop getting louder and louder. "You love it."

At this angle Sans can practically feel Papyrus in his throat, which he likes just fine. He rocks slow and lazy and groans at the friction. "I ain't complainin'."

Papyrus lets out a long impatient sigh that hitches in the middle when Sans tightens on him hard. "At least try not to sound like drunk city trash."

"You got your dick in me, asshole, you want fucking Shakespeare?" Sans bites Papyrus's chest, getting mostly shirt but scraping his teeth across a couple ribs. Papyrus makes a noise that, were he not so great and terrible, would be a moan. "Alas, poor your-dick, I knew it super well, Horatio--"

Then Sans is on his back with Papyrus on top of him again, Papyrus with evil glee in his eyes. Unlike earlier, when they were on the floor, Sans has got his legs wrapped around Papyrus and so he can rut against him, shameless.

"Open your mouth," Papyrus says. He's breathing heavy and rough now, blushing hot under the blood on his face.

Sans does, sticking his tongue out flat because he's being so very cooperative. When Papyrus lifts the soul to his open mouth, Sans digs his fingers into Papyrus's arms but doesn't protest. He doesn't want Papyrus to stop feeding him this lush red magic, keeping him in his animal body with no room for the fucked up sharp things in his head, but he's not going to fucking cling and sniffle about it.

Papyrus's expression darkens for a second, love like a hand around Sans's throat. Then he puts the soul on Sans's tongue like some fucked up communion wafer and kisses him, all tongue and hunger.

It turns out that Papyrus was being gentle.

Papyrus rolls over him, an ocean, dark pressure and heat. Papyrus is in him, cunt and mouth and soul and head, mindfucking him slow. Sans is only what Papyrus makes him, what Papyrus wants, clawing his back and making wet inarticulate noises like an animal.

Papyrus wants him to come, and Sans does it screaming, dragging Papyrus down with him. Then again. Again. Again. There's just enough left of Sans to be afraid that it'll never stop, that they'll get stuck in a Mobius loop and fuck themselves to death, and enough to hope for it. He's close to choking on the slick from his own dripping soul before it finally, blessedly, awfully stops.

When Papyrus comes up for air, Sans pulls him back down with graceless hands. Sans licks the blood off Papyrus's face, leaving streaks of silver. Papyrus is trembling all over, sweating, beautiful.

"There you are," Papyrus says, like Sans has been lost or hiding. "That's good, Sans."

Not real sure what he's agreeing to, Sans nods dizzily, his mouth full. Papyrus isn't in his head but he's screaming _come back_ down the disconnected wires. Papyrus might've just overwritten him, moved all the furniture around in Sans's brain until it's to Papyrus's liking, and he doesn't give one single fuck. He can feel the first stirrings of his usual sweaty anxiety creeping back. 

Indulgently, Papyrus reaches into Sans's mouth and scoops out his soul. The touch of his fingers makes Sans's head snap back. If they hadn't moved to the bed, Sans would've concussed himself. Papyrus doesn't fuck around, just puts his hand under Sans's ribs like it belongs there and replaces his soul. 

"I don't usually have to tell you to swallow," Papyrus says, without the usual edge of irritation. Almost _mellow_ , for him. When Sans swallows, Papyrus touches his face. "Good.”

That yanks Sans back a little from the blurry edges of exhaustion. Papyrus telling him he's good three times in one night is apocalypse territory. Somebody's got to be dying. Thick-tongued, he asks, "Pap?"

"Shut up." Papyrus pulls out of him and hauls Sans around like a slab of meat until he's pressed up against Sans's back, holding him a little too hard. Sans is in the wet spot, of fucking course. "Go to sleep or I'm smothering you with a pillow."

Yeah. Sleep, Sans is good at. He can even do with his eyes closed.

**Author's Note:**

> content warnings: past sexual assault by Gaster, flashback to Gaster being murdered by Papyrus, past prostitution by Sans, sex while in an altered state
> 
> "If we live to see the other side of this  
> I will remember your kiss  
> So do it with your mouth open  
> And take your foot off of the brake, for Christ's sake!"  
> \- Dilaudid, The Mountain Goats


End file.
